Wrist pin and connecting rod assembly



May 29, 1951 L. M. KURTZ 2,554,992

v WRIST PIN AND coNNEcTING Ron ASSEMBLY ,A

Filed oct. 29. 1948 Irverwcor L ,Owell M. Kurtz,

l-I is Attorney.

Patented Vay r2*'9, 195i WRIST PIN AND CONNECTING ROD ASSEMBLY Lowell M. Kurtz, Erie, Pa., assigner to General Electric Company, a corporation of New York Application October 29, 1948, Serial No. 57,343

`l Claims.

l Myinvention relates to compressors or the rlike and more particularly to a self-aligning Wrist pin and connecting rod assembly for such apparatusl It is an object of my invention to provide an Y improved wrist pin and connecting rod construction in which the parts are easily assembled and are self-aligning.

Further objects and advantages of my invention willbecome apparent as the following deing in which Fig. 1 is a sectional elevation view of ia portion of a compressor incorporating my invcntion; Fig. 2 is an enlarged sectional view of a portion of the apparatus shown in Fig. l; and Fig. 3 is aside elevation View of the portion shown `in Fig. 2.'v

Referring to- Fig. 1, there is shown a compressorwhich may be used, for example, in a refrigerating system. The compressor includes a frameI lhaving a cylinder 2, within which is received a reciprocating piston 3. The cornpress'r maybe driven by a motor (not shown) connected to the crankshaft 4. The crankshaft is mounted in suitable bearings 5 and v(. Power is transmitted from the crankshaft to the piston through a connecting rod I which is mounted on a bearing 8 provided on the crank arm 9.

Because of manufacturing tolerances there may be a slight variation in the various parts which make up the complete assembly and the wrist pin may not always be exactly parallel with the crank arm. It is accordingly desirable to provide for self-alignment in order to overcome any adverse effect of such variations. In order to provide for self-alignment between the connecting rod and the piston, the wrist pin and connecting rod assembly illustrated in detail in Fig. 2 is employed. The piston 3 includes a lateral passage I0 within which is received a wrist pin I I. The wrist pin vided with an opening I4. This opening is in general registry with the recessv I2 but, in the assembled position of the connecting rod, isk displaced below the center line of the elongated-recess I2. In order to retain the wrist pin andthe connecting rod in engagement a pin I5 extends longitudinally within the recess I2 and Apasses through the opening I4. l

In order to assist in securing self-alignment of the connecting rod and wrist pin assemblya second recess I6 is provided within the wrist pinII, this recess extending laterally upward from the elongated recess I2 and being located generally in line with the passage I3. The closed end or top of the recess I6 is formed in a V-shaped cross section, as indicated by II, and the top` IS of the connecting rod which is adapted to engage the bottom I1 of the recess is curved so as to allow for self-aligning movement of the connecting rod relative to the wrist pin. Although the top of the recess IS is shown as V-shaped in cross section, it will be apparent that this surface could be cylindrical to match the top surface I8 of the connecting rod.

In order to maintain the connecting rod and wrist pin in engagement along the adjacent surfaces I1 and IS, a construction is provided for bowing the pin I5 and placing the pin under stress. To eiect this result, the lefthand end of the elongated recess I2 is tapered as indicated by I9 to provide an inclined surface. One end 2E) of the pin I5 is arranged to engage the inclined surface I9 in the assembled position. In order to engage the opposite end 2l of the pin I5 and to impart the bowed shape to the pin aplug or cam member 22 is provided. This plug is forced into position within the open end of the recess I2 and may be peened or otherwise secured to the Ywrist pin I I. The plug 22 is generally hollow and is provided internally with an inclined or tapered vsurface 23.

In assembling, the connecting rod is first placed with its upper end extending transversely into the elongated recess I2 and with the surfaces Il and I8 in engagement. The pin I5 is then inserted into the elongated recess I2 and through the Vopening Il in the connecting rod, the end 29 of the pin riding up on the inclined surface I9. The plug'22 is then inserted within the elongated recess I2, the lower end of the inclined surface 23 of the plug being inserted beneath the end 'ZI of the pin. To facilitate insertion of the lower end of the inclined surface 23 of the plug beneath the /end of the pin I5, the end 2| of the pin is chamfered, as indicated by 24. If desired, the other end at the pin may be similarly chamfered, as indicated by 25. As the plug is forced into the position shown in Fig. 2, the end 2I of. the pin gradually rides up the inclined surface 23 and a resulting bowing is imparted to the pin I5. This places the pin under stress and causes the pin to maintain the adjacent surfaces I'I and I8 of the wrist pin and connecting rod respectively in firm engagement. The pin I5 is preferably stressed beyond its elastic limit so that the stress in the.

pin in the assembled position may be uniform regardless of variations in manufacture. In lieu of inserting the pin I5 and then forcing the inclined surfaces 23 of plug under the end 2i of the pin, the end 2| of the pin may rstbe placed Within the plug 22 and then the end 20 passed through the opening I4 and into engagement with the inclined surface I9.

In order to further facilitate self-alignment, the connecting rod is recessed, as indicated by 26 and 21, to provide a surface 28 of relatively small width for engagement with the pin I5. This surface is preferably curved or chamfered to further facilitate the self-alignment.

The elongate-d recess I2 in the wrist pin may be formed by drilling from the righthand end of the wrist pin, as viewed in Fig. 2. The inclined surface I9 at the lefthand end of the recess can be readily provided by a suitable tapered drill. However, it is obvious that, if desired, a cylindrical passage may be drilled en tirelythrough the wrist pin, and a plug similar to plug 22 may be provided at the left end.

It will be noted that in the construction described, the top of the connecting rod is received within the wrist pin and does not extend beyond the top surface of the wrist pin. Accordingly, the top surface of the wrist pin is enabled to engage the cooperating surface of the passage I0 in the piston throughout the length of the wrist pin, thereby reducing the load per square inch on the wrist pin and affording longer wearing qualities.

While I have shown and described a specific embodiment of my invention, I do not desire my invention to be limited to the particular construction shown and I intend, by the appended claims, Ato cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A wrist pin and connecting rod assembly including a wrist pin having an elongated recess therein, a connecting rod having one end extendingl transversely into said recess, said connecting rod having an opening therein, a pin disposed within said recess and extending through said opening, and a cam member forced into position within one end of said. recess for engaging one end of said pin, said pin being forced into bowed shape by said cam member whereby said pin is placed under stress to retain said wrist pin and said connecting rod in engagement.

2. A wrist pin and connecting rod assembly including a wrist pin having an elongated recess therein, a conne-sting rod having one end extending transversely into said recess, said connecting rod having an opening therein, a pin disposed within said recess and extending through said opening, and a cam member forced into position within one end of said recess for engaging one end of said pin, said pin being forced into bowed shape by said cam member whereby said pin is placed under stress to retain 4 said wrist pin and said connecting rod in en# gagement, said pin being stressed beyond its elastic limit.

3. A wrist pin and connecting rod assembly including a wrist pin having an elongated recess therein, a connecting rod having one end extending transversely into said recess, said connecting rod having an opening therein, a pin disposed within sai-d recess and extending through said opening, and a plug forced into position within one end 'of said recess, said plug having an internal inclined surface for engaging one end of said pin, said pin being forced into bowed shape by engagement with said inclined surface whereby said pin is placed under stress to retain said wrist pin and said connecting rod in engagement.

4. A wrist pin and connecting rod assembly including a wrist pin having an elongated recess therein, a connecting rod having one end extending transversely into said recess, said connecting rod having an opening therein, a pin disposed within said recess and extending through said opening, and a plug forced into position within one end of said recess, said plug having an internal inclined surface for engaging one end of said pin, said pin being forced into bowed shape by engagement with said inclined surface whereby said pin is placed under stress to retain said wrist pin and said connectingrod in engagement, said pin being stressed beyond its elastic limit.

5. A wrist pin and connecting rodV assembly including a wrist pin having an elongated recess therein, said recess having an open end, a connecting rod having one end extending transversely into said recess, said connecting rod having an opening therein, said opening being in registry with said elongated4 recess but displaced from the center line thereof, a pin disposed within said recess and extending through said opening, and a cam member forced into position within said open end of said recess for engaging one end of said pin, said pin being forced into bowed shape by said cam member whereby said pinis placed under stress to retain said wrist pin and said connecting rod in en'- gagement. l

6. A wrist pin and connecting rod assembly including a wrist pin having an elongated recess therein, said recess having a closed end and being provided with an inclined surface adjacent said closed end, a connecting rod having one end extending transversely into said recess, said connecting rod having an opening therein, a pin disposed within said recess and. extending through said opening, one end of said pin engaging said inclined surface,` said recess having an open end, and a cam member forcedinto position within said open end of saidrecess for engaging the other end of said pin, said pin being forced into bowed shape by engagement with said inclined surface and said cam member whereby said pin is placed under stress to retain said wrist pin and said connecting rod in ven"- gagement. .i

7. A wrist pin and connecting rod assembly including a wrist pin having an elongated recess therein, said recess having a closed end andv beging provided'with an inclined surface adjacent said closed end, a connecting rod having one end extending transversely into said recess, said con'- necting rod having an opening therein, a pin disposed within said recess and extending through said opening, one end of said pin' engaging said inclined surface, said recess having an open end, and a plug forced into position within said open end of said recess, said plug having an internal inclined surface, one end of said pin engaging said inclined surface of said recess and the other end of said pin engaging said inclined surface of said plug, said pin being forced into bowed shape by engagement with said inclined surfaces whereby said pin is placed under stress to retain said wrist pin and said connecting rod in engagement.

8. A wrist pin and connecting rod assembly including a wrist pin having a longitudinal elongated recess therein, said recess having a closed end, said closed end of said recess being tapered to provide an inclined surface, a connecting rod having one end extending transversely into said recess, said connecting rod having an opening therein in registry with said recess but displaced from the center line thereof, a pin disposed within said recess and extending through said opening, one end of said pin engaging said inclined surface, said recess having an open end, and a plug for closing said open end of said recess, said plug having an internal inclined surface for engaging the other end of said pin, said pin being forced into bowed shape by engagement with said inclined surfaces whereby said pin is placed under stress to retain said wrist pin and said connecting rod in self-aligning engagement.

9. A self-aligning wrist pin and connecting rod assembly including a wrist pin having a longitudinal elongated recess therein, a second recess in said wrist pin extending laterally from said elongated recess, the end of said second recess being V-shaped in cross section in a vertical plane extending through the axis of said wrist pin, a connecting rod extending transversely of said elongated recess and having its end in engagement with said V-shaped end of said second recess, said end of said connecting rod having a curved surface to facilitate self-alignment, said connecting rod having an opening therethrough, said opening being in registry with said elongated recess but displaced from the center line thereof, a pin disposed within said elongated recess and extending through said opening, and a cam member forced into position within one end of said elongated recess for engaging one end of said pin, said pin being forced Iinto bowed shape by said cam member whereby said pin is placed under stress to retain said wrist pin and said connecting rod in engagement.

10. A self-aligning wrist pin and connecting rod assembly including a wrist pin having a longitudinal elongated recess therein, a second recess in said wrist pin extending-laterally from said elongated recess, a connecting rod extending transversely of said elongated recess and having its end extending into said second recess, said end of said connecting rod having a curved surface to facilitate self-aligning engagement with said second recess, said connect- --ing rod having an opening therethrough, said opening being in registry with said elongated recess but displaced from the center line thereof, a pin disposed within said elongated recess and extending through said opening, the surface of said connecting rod adjacent said opening being curved to facilitate self-alignment of said connecting rod and said wrist pin, and cam member forced into position within one end of said recess for engaging one end of said pin, said pin being forced into bowed shape by said cam member whereby said pin is placed understress to retain said wrist pin and said connecting rod in engagement.

LOWELL M. KURTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,480,185 Setter Jan. 8, 1924 1,921,607 Curtis Aug. 8, 1933 

